Power operated belt sanding machine



July 11, 1961 w, ADDIS 2,991,595

POWER OPERATED BELT SANDING MACHINE Filed Nov. 4, 1959 2 Sheets-Sheet 1 IN VEN TOR. WND l A- ADD/5 July 11, 1961 w. A. ADDIS 2,991,595

POWER OPERATED BELT SANDING MACHINE Filed Nov. 4, 1959 2 Sheets-Sheet 2 INVENTOR 3 ld/[NDELL A- App/s BY 4 7M Mpg: V46 ATTORNEYJ United States Patent 2,991,595 POWER OPERATED BELT SANDING MACHINE Wendell A. Addis, Deerfield, Mass., assignor to Millers Falls Company, Greenfield, Mass., a corporation of Massachusetts Filed Nov. 4, 1959, Ser. No. 850,930 Claims. ((11. 51-170) This invention relates to hand operated power driven belt sanding machines and more particularly to power transmissions for such machines.

The primary object of this invention is to provide a novel power transmission for a belt sander tool which results in a sander construction of compact overall size.

The above and other objects and advantages of this invention will be more readily apparent from a reading of the following specification from which the following drawings are a part:

FIG.1 is a side elevation of a sanding machine embodying the present invention;

FIG. 2 is a side elevation of the other side of the sanding machine shown in FIG. 1;

FIG. 3 is a section taken along the lines 33 of FIG. 2, with the sanding machine disposed in a position as shown in FIG. 1, and

FIG. 4 is a fragmentary sectional view showing details of construction.

The sanding machine embodying this invention comprises an integral frame having a relatively flat top wall 8, a depending side wall 10, a bottom wall 12 which extends outwardly of the side wall 8 in spaced parallel relationship with the top wall 10, and a motor housing 14 located on a recessed central portion of top wall 8. A handle 15 extends rearwardly from the motor housing 14 and receives a power supply cable 16 which is connected to a drive motor within the housing 14 by a switch which may be actuated by a trigger 18.

A drive roll 20 is mounted adjacent the rear end of the sander frame and an idler roll 22 is supported at the front end of the sander by a yoke 24 which extends forwardly from a guide block 26 mounted on the bottom wall 12. An endless abrasive belt 27 may be trained over the rolls 20 and 22 and its lower reach engaged with the under surface of a pressure plate 28 which is attached to the bottom wall 12. An operating lever 29 is provided for the fore and aft movement of the roll 22 facilitating the removal or placement of an abrasive belt on the rolls 20 and 22.

The power transmission structure of the present in vention is best shown in FIGS. 2 and 3 connecting a motor armature 30 in driving relationship with the drive roll 20. The motor armature 30 is mounted within the housing 14 and includes an armature shaft 32 disposed transversely of the sander frame and extending outwardly of the side wall 10. A cog pulley 34 is secured on the outer end of the shaft 32 and a cog belt 36 is engaged with the pulley 34 and extends downwardly and rearwardly within a removable cover 41 and is engaged with another pulley 38 which is splined on the outer end portion of a drive shaft 49 (FIG. 3) and secured in place by a screw 39. The central portion of the drive shaft 40 is journaled within bosses 42 and 43 formed on the side wall and the shaft 40 is disposed parallel with the motor shaft 32. The other end of the drive shaft 40 extends inwardly of the boss 43 and is received within the internally cupped hollow end portion of the drive roll 20. The roll 20 is journaled on a drive roll shaft 44 which is supported by the boss 43 in closely spaced parallel relationship with the drive shaft 40. A ring gear 46 is secured on a shouldered inner wall section of the roll '20 and a pinion gear 48 formed on the inner end portion of the drive shaft 40 meshes with the internal Patented July 11, 1961 ring gear 46 for driving the roll 20 and the abrasive belt 27 tensioned over the idler roll 22.

The over-all compact size of the sanding machine which embodies the present invention is realized by the novel construction and disposition of the gear drive trans mission. The side wall 10 of the sander frame is integrally formed with the boss 43 extending inwardly from the side wall 10 and terminating short of the center line of the sander. The boss 43 is of stepped cylindrical construction and includes an inner section of relatively large diameter which extends inwardly from the side wall 10, an intermediate portion of relatively smaller diameter and an outer portion of substantially smaller diameter than the intermediate portion.

The boss 43 is provided with an axial bore 50 in which the inner portion of the roll support shaft 44 is anchored and a second bore '52 which is radially ofiset from and parallel with the axial bore 50, throughthe inner and intermediate portions of the boss 43. The distance between the centers of bores 50 and 52 is substantially less than the inner radius of the drive roll 20. The boss 42 extends outwardly from side wall 10 and is formed with a shouldered bearing seat 54 aligned with the bore 52. The central section of the drive shaft 40 is journaled at spaced locations by a ball bearing 56'located in the seat 54 and a needle bearing 58 set in the bore 52. Since the bore 52 and the seat 54 are provided in the integral bosses 43 and 42 respectively, the bearings 56 and '58 are easily brought into correct alignment, an advantage from the standpoint of assembly operations.

The secured portion of shaft 44 disposed in boss 43 and the overlapping coextensive portion of shaft 40 both ex tend coextensively within boss 43 for a substantial distance and thus provide a compact drive assembly despite the relatively large bearing length of drive shaft 40 and the relatively large secured length of shaft 44.

As seen in FIG. 3 the sandpaper or abrasive belt 27 has a width which may be substantially equal to the length of the drive roll 20 and the latter is provide with a friction sleeve 45 for preventing slippage of the abrasive belt on the drive roll.

With the internal drive of the presen't'invention, the sander thus may have a maximum abrasive belt width and maximum bearing lengths with a minimum overall sander width. Since the gear 48 is disposed in the cupped end of drive roll 26, the assembly may also be of arelatively small height despite a relatively large diameter of drive roll 20.

The drive roll 20 includes a flanged hub portion 60 journaled by needle bearings 62 on the extending portion of the shaft 44. Roll 20 is retained on shaft 44 by means of a cap 64, washer 66 and a nut 68 threaded on the outer end of the shaft, the nut 68 holding the other end of the hub against a collar 70 on shaft 44 adjacent the end face of the boss 43.

The ring gear 46 disposed in a seat provided on the inner surface of the cupped portion of roll 20 is positioned axially on the roll so as to be engaged by the pinion gear-48 which extends from the front face at 72 of the stepped intermediate portion of boss 43.

The stepped construction of the boss serves to provide a gear chamber for pinion 48 and gear 46. Endwise of the ring gear 46 the wall of the cupped portion of roll 20 is shouldered to form a seat for a sealing ring assembly. As best seen in FIG. 4, a pair of rings 73 with facing com plementary tapered sides are press fitted into the shoul dered section with a band 74 of felt held between the rings. Both the rings and felt thus will revolve around the boss. The felt wipes or rubs over the surface of the boss and any heat thus generated is more rapidly dissipated by conduction to the stationary boss than if it were transferred to the roll 20. On the boss inwardly of the sealing ring structureis press-fitted a washer ring 75. The washer is spaced from the roll surface but with a very slight clearance and accordingly a labyrinth is created which has been'found to be-extremely effective in keeping grease from leaking from the gear compartment.

It will be noted by reference to FIG. 2 that the pulley 38 has a substantially larger diameter than the pulley 34 which is secured to the armature shaft 32, thus effecting a substantial reduction in speed from the armature shaft 32 to the drive shaft 40. A further substantial speed reduction is accomplished by the relatively small diameter pinion 48 being in mesh with the relatively large diameter ring gear 46. A substantial speed reduction is thus achieved by the structure disclosed without affecting the overall compact size of the machine as a whole.

What is claimed is:

1. In a hand operated power driven belt sander having an integral frame with atop and depending side wall, drive andidler rolls disposed at the rear and front portions .of said side wall for receiving an endless abrasive belt and a motor mounted on said top wall and disposed with its axis parallel with the axes of said rolls; a power transmission structure comprising a first boss integrally formed on said side wall and extending inwardly therefrom, a first bore axially disposed within said boss, a roll shaft fixed in said bore and having a portion extending therefrom, said drive roll journaled on the extending portion of said roll shaft, a second boss integrally formed on said .side wall and extending outwardly therefrom, said second boss including a recess, a secondbore disposed through said first boss and in communication with said recess, said second bore being adjacent to and parallel with the axial bore of said first boss, a drive shaft journaled at spaced points within said second bore and within said recess, said drive shaft being coextensive with said roll shaft within said first boss and having one end extending outwardly of said second boss for coupling with said motor, the other end of said drive shaft extending inwardly from said first boss and including an integrally formed pinion gear portion, said drive roll including a hollow portion for receiving said first boss, a ring gear disposed on the inner surface of said drive roll and concentrically spaced from said first boss, said ring gear and said pinion gear being in mesh in the space within the loop formed by said abrasive belt, and a seal ring disposed outwardly of said ring gear and engaged with the inner surface of said drive roll and said first boss and forming a closed gear chamber within the hollow portion of said drive roll.

2. In a hand operated power driven belt sander having an integral frame with a top and depending side wall, drive and idler rolls disposed at the rear and front portions of said side wall for receiving an endless abrasive belt and a motor mounted on said top wall and disposed with its axis parallel with the axes of said rolls; a power transmission structure comprising a first boss integrally formed on said side wall and having a steppedcylindrical construction extending inwardly from the side wall and including outer, intermediate and inner portions, the portions of said boss having diameters of decreasing size from the outer to the inner portion, a first bore axially disposed within said boss, a roll shaft fixed in said bore and having a portion extending therefrom, said drive roll 4 journaled on the extending portion of said roll shaft, a second boss integrally formed on said side wall and extending outwardly therefrom, said second boss including a recess, a second bore disposed through the intermediate and outer portions of said first boss and in communication with said recess, said second bore being adjacent to and parallel with the axial bore of said first boss, a drive shaft journaled at spaced points within said second bore and within said recess, said drive shaft being coextensive with said roll shaft within said first boss and having one end extending outwardly of said second boss for coupling to said motor, the other end of said drive shaft extending inwardly from the intermediate portion of said first boss and including an integrally formed pinion gear portion, said drive roll including a hollow portion for receiving the inner and intermediate portions of said first boss, a ring gear disposed on the inner surface of said drive roll and concentrically spaced from the inner portion of said first boss, said ring gear and said pinion gear being in mesh in the space within the loop formed by said abrasive belt, and a seal ring disposed on the intermediate portion of said first boss and engaged with the inner surface of said drive roll, said first boss and seal ring forming a closed gear chamber within the hollow portion of said drive roll.

3. A powerdriven belt sander comprising a frame including a side wall portion, a boss extending inwardly of said side wall, a stationary shaft extending from said boss, an abrasive belt drive roll rotatably mounted on said shaft and having a chamber therein defined by the inner surface of said roll and a transverse 'llub member, a ring gear carried by said roll within said chamber, said boss having portions of reduced diameter telescopically extending into said chamber, a drive shaft journaled in said frame and radially offset from said roll supporting shaft, one end of said drive shaft extending within said chamber, and including a pinion gear meshed with said ring gear for driving said roll, and a sealing ring disposed axially outwardly of said ring gear and pinion and engaged with opposed surfaces of said boss and drive roll, said sealing ring, boss and roll ohamber defining a sealed gear chamber disposed wholly within said drive roll.

4. A power driven belt sander as set forth in claim 3 in which said sealing ring is carried within said drive roll and has an inner surface portion engaged with opposed peripheral portions of said boss.

5. A power driven belt sander as set forth in claim 4 above and further including an annular member mounted on said boss outwardly of said sealing ring and closely adjacent thereto, said annular member serving with said sealing ring to prevent the escape of lubricants from said gear chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,522,068 Morgan Jan. 6, 1925 1,893,937 Chapman Jan. 10, 1933 2,566,809 Risleyet al. Sept. 4, 1951 2,774,198 Emmons Dec. 18, 1956 2,779,205 Block Jan. 29, 1957 FOREIGN PATENTS 352,754 Great Britain July 16, 1931 

